Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<cstdio>
#include<queue>
#include<tuple>

using namespace std;

#define rep(i, n) for(int i = 0; i < n; i++)

int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};

int main(){
	int h, w; scanf("%d %d", &h, &w);
	char s[50][51];
	rep(i, h) scanf("%s", s[i]);
	int b = 0;
	rep(i, h) rep(j, w){
		if(s[i][j] == '#') b++;
	}
	queue<tuple<int, int, int>> q;
	q.push(make_tuple(0, 0, 0));
	bool flag[50][50] = {};
	flag[0][0] = 1;
	int res = -1;
	while(!q.empty()){
		int x, y, t;
		tie(y, x, t) = q.front(); q.pop();
		if(y == h - 1 && x == w - 1){ res = t; break; }
		rep(i, 4){
			int ny = y + dy[i], nx = x + dx[i];
			if(ny < 0 || ny >= h || nx < 0 || nx >= w || flag[ny][nx] || s[ny][nx] == '#') continue;
			q.push(make_tuple(ny, nx, t + 1));
			flag[ny][nx] = 1;
		}
	}
	if(res == -1) puts("-1");
	else printf("%d\n", h * w - b - res - 1);
	return 0;
}